This project is directed to provide some comprehension of the neurochemical mechanisms involved in regulation of sleep and wakefulness by studying turnover of serotonin and dopamine in the brain during these behavioral stages. The turnover of the corresponding amine is estimated in vivo from the rate of appearance of its endogenous metabolite in the perfused CSF compartment during both sleep and wakefulness. The current year was devoted to the development and improvement of techniques. These included setting up procedures for polygraphic recording, perfection of methods for determination of H3-HVA and C14-5HIAA specific radioactivities, and carrying out initial experiments with rabbits to work out conditions for perfusions of the CSF compartment in unanesthetized animals.